CONAKRY--Two people were killed and at least 33 were wounded in Guinea on Friday in clashes between supporters of President Alpha Conde and his main rival before Sunday's election, witnesses and a senior police source said.

Shots were fired, security forces fired teargas and wielded batons outside the house of Conde's rival, Cellou Dalein Diallo, in the capital, while activists armed with stones and clubs roamed the streets, reducing traffic to a minimum, they said.

Eighteen of those wounded were members of the security forces, state television said. There were also clashes in Kerouane and Kissidougou in the southeast of the country, a government source said.

It was not immediately clear what triggered the clashes, but Conde on Thursday rejected a demand by opposition candidates to postpone the vote to allow time to rectify what they said were irregularities in the process. Late on Friday, the constitutional court, which is the election's highest authority, also rejected a request by seven opposition leaders who had argued that the election should be postponed by at least a week to rectify irregularities.

"They attacked us this morning, waking us up with volleys of stones. The attackers were numerous," said one of Diallo's bodyguards, who declined to give his name. There was no immediate comment from the security forces.

The West African country has a history of election violence, and Conde earlier cancelled his last campaign rally due to security concerns, after clashes on Thursday that left at least one dead and 20 injured. Conde is the favourite to win a second term after his election in 2010 ended two years of brutal military rule. Since then, Guinea has been battered by the Ebola epidemic and a slump in global commodities prices that has hit its exports of bauxite.

The president suspended an auction for the right to develop half of Simandou, the world's biggest untapped iron ore deposit, already running well behind a timetable indicated earlier this year by the country's mines minister. Conde gave no reason for the decision, though some analysts say a steep drop in iron ore prices and lawsuits surrounding the deposit may have diminished investors' appetite for the development.

Analysts predict disputes over the election preparations and the eventual results may ignite ethnic violence between the two groups of supporters. Burned shops and cars dotted one Conakry thoroughfare, and Conde supporters sang songs on street corners. "Don't attack anybody but if you are attacked, defend yourself," Diallo said on local radio.

As the tension mounted, Mohammed Ibn Chambas of Ghana, special representative of the United Nations Secretary General, met Diallo, a witness said.